Contacts for electrochemical processing

ABSTRACT

Systems and methods for electrochemically processing a substrate. A contact element defines a substrate contact surface positionable in contact a substrate during processing. In one embodiment, the contact element comprises a wire element. In another embodiment the contact element is a rotating member. In one embodiment, the contact element comprises a noble metal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/211,626, filed Aug. 2, 2002, now U.S. Pat. No. 7,125,477, which is acontinuation in part of U.S. patent application Ser. No. 10/033,732,filed Dec. 27, 2001, now U.S. Pat. No. 7,066,800, which is acontinuation in part of U.S. patent application Ser. No. 09/505,899,which was filed Feb. 17, 2000, now issued as U.S. Pat. No. 6,537,144,all of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to polishing, planarization,plating and combinations thereof. More particularly, the inventionrelates to contacts for electrochemical mechanical polishing and/orelectropolishing.

2. Description of the Related Art

Sub-micron multi-level metallization is one of the key technologies forthe next generation of ultra large-scale integration (ULSI). Themultilevel interconnects that lie at the heart of this technologyrequire planarization of interconnect features formed in high aspectratio apertures, including contacts, vias, trenches and other features.Reliable formation of these interconnect features is very important tothe success of ULSI and to the continued effort to increase circuitdensity and quality on individual substrates and die.

In the fabrication of integrated circuits and other electronic devices,multiple layers of conducting, semiconducting, and dielectric materialsare deposited on or removed from a surface of a substrate. Thin layersof conducting, semiconducting, and dielectric materials may be depositedby a number of deposition techniques. Common deposition techniques inmodern processing include physical vapor deposition (PVD), also known assputtering, chemical vapor deposition (CVD), plasma-enhanced chemicalvapor deposition (PECVD), and electro-chemical plating (ECP).

As layers of materials are sequentially deposited and removed, theuppermost surface of the substrate may become non-planar across itssurface and require planarization. An example of non-planar process isthe deposition of copper films with the ECP process in which the coppertopography simply follows the already existing non-planar topography ofthe wafer surface, especially for lines wider than 10 microns.Planarizing a surface, or “polishing” a surface, is a process wherematerial is removed from the surface of the substrate to form agenerally even, planar surface. Planarization is useful in removingundesired surface topography and surface defects, such as roughsurfaces, agglomerated materials, crystal lattice damage, scratches, andcontaminated layers or materials. Planarization is also useful informing features on a substrate by removing excess deposited materialused to fill the features and to provide an even surface for subsequentlevels of metallization and processing.

Chemical Mechanical Planarization, or Chemical Mechanical Polishing(CMP), is a common technique used to planarize substrates. CMP utilizesa chemical composition, typically a slurry or other fluid medium, forselective removal of materials from substrates. In conventional CMPtechniques, a substrate carrier or polishing head is mounted on acarrier assembly and positioned in contact with a polishing pad in a CMPapparatus. The carrier assembly provides a controllable pressure to thesubstrate, thereby pressing the substrate against the polishing pad. Thepad is moved relative to the substrate by an external driving force. TheCMP apparatus effects polishing or rubbing movements between the surfaceof the substrate and the polishing pad while dispersing a polishingcomposition to affect chemical activities and/or mechanical activitiesand consequential removal of materials from the surface of thesubstrate.

Another planarization technique is Electro Chemical Mechanical Polishing(ECMP). ECMP techniques remove conductive materials from a substratesurface by electrochemical dissolution while concurrently polishing thesubstrate with reduced mechanical abrasion compared to conventional CMPprocesses. The electrochemical dissolution is performed by applying abias between a cathode and a substrate surface to remove conductivematerials from the substrate surface into a surrounding electrolyte.Typically, the bias is applied to the substrate surface by a ring ofconductive contacts in a substrate support device, such as a substratecarrier head. Mechanical abrasion is performed by positioning thesubstrate in contact with conventional polishing pads and providingrelative motion there between.

Despite some advantages over other polishing techniques, conventionalECMP poses some problems of its own. One important aspect of ECMP whichpresents difficulties is maintaining a sufficient and uniform bias onthe substrate. In this regard, the use of a contact ring has provenundesirable in some cases because such devices exhibit non-uniformdistribution of current over the substrate surface, which results innon-uniform dissolution. Additionally, the polishing pad may be composedof insulative materials that may interfere with the application of biasto the substrate surface and result in non-uniform or variabledissolution of material from the substrate surface.

As a result, there is a need for an improved polishing article for theremoval of conductive material on a substrate surface.

SUMMARY OF THE INVENTION

The present invention provides methods of electrochemical processing,electrochemical processing systems and polishing articles used withelectrochemical processing systems.

One embodiment provides a polishing article for electrochemicalmechanical polishing, comprising: a body defining a outer surface; and aconductive contact element at least partially disposed through the padbody and positionable in a substrate contact position, and wherein theconductive contact element comprises at least two wires in contact withone another and defining a substrate contact surface. In one embodiment,the body is a polishing pad and the outer surface is a polishingsurface.

Another embodiment of a polishing article for electrochemical processingcomprises: a body defining a outer surface; and a conductive contactelement at least partially disposed through the pad body andpositionable in a substrate contact position, and wherein the conductivecontact element comprises a wire portion and a relatively enlargedportion disposed on the wire portion and defining a substrate contactsurface. In one embodiment, the body is a polishing pad and the outersurface is a polishing surface.

Another embodiment provides a current conducting assembly forelectrochemical processing, comprising: an insulating member defining aplurality of contact element retaining openings; a conducting surfacedisposed on the insulating member; and a plurality of contact elementseach having a first end disposed in one of the plurality of contactelement retaining openings and a second end disposed on the conductingsurface, wherein a portion of each of the plurality of contact elementsdefines a substrate contact surface.

Yet another embodiment provides a polishing article for electrochemicalprocessing, comprising: a body defining an outer surface; and anelongated assembly disposed in the body and at least partially recessedbelow the polishing surface. The elongated assembly comprises: at leastone elongated conductive member; and a conductive wire wound around andin contact with the least one elongated conductive member and forming atleast two loops each comprising a portion at least partially extendingover the outer surface, wherein the portion of the at least two loopsdefines a substrate contact surface.

Yet another embodiment provides a polishing article for electrochemicalprocessing, comprising: a body defining an outer surface; and anelongated assembly disposed in the body and at least partially recessedbelow the outer surface. The elongated assembly comprises: at least oneelongated conductive member; and a noble-metal-containing conductivesheet wrapped around and in contact with the least one elongatedconductive member and defining a substrate contact surface.

Yet another embodiment provides an electrochemical processing system,comprising: a cell body defining an electrolyte-containing volume; anelectrode disposed in the electrolyte-containing volume; a polishing paddisposed in the electrolyte-containing volume and comprising: (i) a padbody defining a polishing surface; and (ii) a conductive contact elementat least partially disposed through the pad body and extending over thepolishing surface, wherein the contact element comprises at least twowire strands; and a power supply coupled to the electrode and thecontact element.

Yet another embodiment provides a method for electrochemicallyprocessing a substrate comprising a conductive surface, the methodcomprising: providing a pad defining a polishing surface and comprisinga conductive contact element disposed through the pad, wherein theconductive contact element comprises at least two wires defining asubstrate contact surface at an upper end; placing the conductivesurface of the substrate in contact with the polishing surface of padand with the substrate contact surface of the conductive contact elementin presence of electrolytic fluid; and providing a bias to the substratevia the conductive contact element.

Yet another embodiment provides a polishing article for electrochemicalprocessing, comprising: a body defining an outer surface; and aconductive rotating contact element rotatably disposed in the body andhaving at least a portion positionable in a substrate contact position(e.g., at or over the outer surface) in which the conductive rotatingcontact element contacts a substrate surface during electrochemicalprocessing. In some embodiments, the contact pressure is controlled toprovide good and reliable electrical contact while preventing damage tothe substrate surface being polished.

Yet another embodiment provides a current conducting assembly forelectrochemical processing, comprising: a housing; and acurrent-providing conductive rotatable contact element rotatablydisposed in the housing and having at least a substrate contact portionpositionable at a substrate contact position to rotatably contact asubstrate surface during electrochemical mechanical polishing.

Still another embodiment provides an electrochemical processing system,comprising: a cell body defining an electrolyte-containing volume; anelectrode disposed in the electrolyte-containing volume; a polishing paddisposed in the electrolyte-containing volume and comprising: (i) a padbody defining a polishing surface; and (ii) at least one conductiverotatable contact element at least partially disposed through the padbody and extending over the polishing surface and rotatable with respectto the polishing pad, wherein the conductive rotatable contact elementis adapted to contact a substrate surface during electrochemicalprocessing and rotate relative to the substrate surface; and a powersupply coupled to the electrode and the contact element.

Still another embodiment provides a contact assembly for electrochemicalprocessing, comprising: a housing comprising a seat and defining apassageway having a restricted opening at one end defined by the seat; acontact element connectable to a power supply; and a conductiverotatable contact element rotatably disposed in the passageway andhaving a degree of axial freedom therein and having at least a substratecontact portion positionable beyond the housing and adapted to rotatablycontact a substrate surface during electrochemical processing andwherein the conductive rotatable contact element is positionable in atleast a first position to be separated from the contact element and asecond position to be in contact with the contact element.

Yet another embodiment provides a method for electrochemical processinga substrate comprising a conductive surface, the method comprising:providing a pad defining a polishing surface; providing a conductiverotating contact element rotatably disposed in the pad body; placing aconductive surface of the substrate in contact with the polishingsurface of pad and the conductive rotating contact element; delivering acurrent to the conductive rotating contact element; and causing relativemotion between the substrate and the pad, whereby the conductiverotating contact element is rotated over the substrate while in contactwith the substrate.

Still another embodiment provides an electrochemical processing contactassembly, comprising: a support body; a conductive housing disposed inthe support body; a removable insulative plug disposed in the supportbody; and an electrically conductive wire contact wrapped about theremovable insulative plug and forming an arch defining a substratecontact surface at an apex.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features, advantages andobjects of the present invention are attained and can be understood indetail, a more particular description of the invention, brieflysummarized above, may be had by reference to the embodiments thereofwhich are illustrated in the appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a plan view of one embodiment of a processing apparatus of theinvention;

FIG. 2 is a sectional view of one embodiment of an ECMP station;

FIG. 3 is a partial perspective view of one embodiment of the polishingarticle having an exposed wire contact element disposed therethrough;

FIG. 4 is a partial perspective view of the polishing article of FIG. 3illustrating one embodiment for securing the wire contact element;

FIG. 5 is a partial perspective view of the polishing article of FIG. 3illustrating another embodiment of the wire contact element;

FIG. 6 is a partial perspective view of the polishing article of FIG. 3illustrating another embodiment of the wire contact element;

FIG. 7A is a top plan view of one embodiment of a wire contact elementcarrier;

FIG. 7B is a side cross-sectional view of the wire contact elementcarrier of FIG. 7A;

FIG. 8A is a partial perspective view of another embodiment of a wirecontact element carrier disposed on a polishing article;

FIG. 8B is an exploded perspective view of the element carrier of FIG.8A;

FIG. 9 is an exploded perspective view of a wire contact elementcarrier;

FIG. 10 is perspective view of another embodiment of a wire contactelement carrier polishing article having contact elements with nodulesformed thereon;

FIG. 11 is a perspective view of another embodiment of a wire contactelement carrier disposable on a polishing article;

FIG. 12 is an exploded perspective view of the element carrier of FIG.11;

FIG. 13 is a schematic side view of a roller contact assembly disposedin a polishing article and configured for wafer face up polishing;

FIG. 14 is a schematic side view of a roller contact assembly disposedin a polishing article and configured for wafer face down polishing;

FIG. 15 is a schematic side view of a roller contact assembly disposedin a polishing article and having three stacked roller contacts and aheight adjustment mechanism;

FIG. 16 is a perspective view of a polishing article comprising a rollerbearing assembly;

FIG. 17 is a front view of the roller bearing assembly of FIG. 16;

FIG. 18A is a front view of another embodiment of the roller bearingassembly of FIG. 16;

FIG. 18B is a side view of the roller bearing assembly of FIG. 18A;

FIG. 19 is partial perspective view of another embodiment of a polishingarticle having ball bearing contact assemblies;

FIG. 20 is a side sectional view of the ball bearing contact assembly ofFIG. 19;

FIG. 21 is a side sectional view of another embodiment of the ballbearing contact assembly of FIG. 19;

FIG. 22 is a an exploded view of one embodiment of the ball bearingcontact assembly of FIG. 21;

FIG. 23 is a perspective view of another embodiment of the ball bearingcontact assembly of FIG. 21;

FIG. 24 is a side sectional view of another embodiment of the ballbearing contact assembly of FIG. 19;

FIG. 25 is a plan view of an embodiment of a polishing article having apower control assembly; and

FIG. 26 is a plan view of another embodiment of a polishing articlehaving a power control assembly.

To facilitate understanding, identical reference numerals have beenused, wherever possible, to designate identical elements that are commonto the figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides methods of polishing, electropolishingsystems and polishing articles used with electropolishing systems.

The words and phrases used herein should be given their ordinary andcustomary meaning in the art by one skilled in the art unless otherwisefurther defined. Chemical-mechanical polishing should be broadlyconstrued and includes, but is not limited to, abrading a substratesurface by chemical activities, mechanical activities, or a combinationof both chemical and mechanical activities. Electropolishing should bebroadly construed and includes, but is not limited to, planarizing asubstrate by the application of electrical and/or electrochemicalactivity. Electrochemical mechanical polishing (ECMP) should be broadlyconstrued and includes, but is not limited to, planarizing a substrateby the application of electrochemical activity, mechanical activity, ora combination of both electrochemical and mechanical activity to removematerials from a substrate surface. Electroplating should be broadlyconstrued and includes, but is not limited to, electrochemicallydepositing material on a substrate by the application of electrochemicalactivity, mechanical activity, or a combination of both electrochemicaland mechanical activity. Electrochemical mechanical plating process(ECMPP) should be broadly construed and includes, but is not limited to,electrochemically depositing material on a substrate and concurrentlyplanarizing the deposited material by the application of electrochemicalactivity, mechanical activity, or a combination of both electrochemicaland mechanical activity.

Anodic dissolution should be broadly construed and includes, but is notlimited to, the application of an anodic bias to a substrate directly orindirectly which results in the removal of conductive material from asubstrate surface and into a surrounding electrolyte solution.

In general, any of the above-defined polishing techniques may be used,individually or in combination. Further, it is contemplated thatpolishing and plating may occur simultaneously, alternately orexclusively. The foregoing embodiments are broadly and collectivelycharacterized as electrochemical processing.

FIG. 1 depicts a processing apparatus 100 having at least one stationsuitable for electrochemical deposition and chemical mechanicalpolishing, such as electrochemical mechanical polishing (ECMP) station102 and at least one conventional polishing or buffing station 106disposed on a single platform or tool. One polishing tool that may beadapted to benefit from the invention is a REFLEXION® chemicalmechanical polisher available from Applied Materials, Inc. located inSanta Clara, Calif. Another polishing tool that may be adapted tobenefit from the invention is a MIRRA MESA® chemical mechanical polisheravailable from Applied Materials, Inc. located in Santa Clara, Calif.

The exemplary apparatus 100 generally includes a base 108 that supportsone or more ECMP stations 102, one or more polishing stations 106, atransfer station 110 and a carousel 112. The transfer station 110generally facilitates transfer of substrates 114 to and from theapparatus 100 via a loading robot 116. The loading robot 116 typicallytransfers substrates 114 between the transfer station 110 and a factoryinterface 120 that may include a cleaning module 122, a metrology device104 and one or more substrate storage cassettes 118. One example of ametrology device 104 is a NovaScan™ Integrated Thickness Monitoringsystem, available from Nova Measuring Instruments, Inc., located inPhoenix, Ariz.

Alternatively, the loading robot 116 (or factory interface 120) maytransfer substrates to one or more other processing tools (not shown)such as a chemical vapor deposition tool, physical vapor depositiontool, etch tool and the like.

In one embodiment, the transfer station 110 comprises at least an inputbuffer station 124, an output buffer station 126, a transfer robot 132,and a load cup assembly 128. The loading robot 116 places the substrate114 onto the input buffer station 124. The transfer robot 132 has twogripper assemblies, each having pneumatic gripper fingers that hold thesubstrate 114 by the substrate's edge. The transfer robot 132 lifts thesubstrate 114 from the input buffer station 124 and rotates the gripperand substrate 114 to position the substrate 114 over the load cupassembly 128, then places the substrate 114 down onto the load cupassembly 128.

The carousel 112 generally supports a plurality of polishing heads 130,each of which retains one substrate 114 during processing. The carousel112 transfers the polishing heads 130 between the transfer station 110,the one or more ECMP stations 102 and the one or more polishing stations106. One carousel 112 that may be adapted to benefit from the inventionis generally described in U.S. Pat. No. 5,804,507, issued Sep. 8, 1998to Tolles et al., which is hereby incorporated by reference to theextent it is not inconsistent with the claims and disclosure herein.

Generally, the carousel 112 is centrally disposed on the base 108. Thecarousel 112 typically includes a plurality of arms 138. Each arm 138generally supports one of the polishing heads 130. One of the arms 138depicted in FIG. 1 is not shown so that the transfer station 110 may beseen. The carousel 112 is indexable such that the polishing head 130 maybe moved between the stations 102, 106 and the transfer station 110 in asequence defined by the user.

Generally the polishing head 130 retains the substrate 114 while thesubstrate 114 is disposed in the ECMP station 102 or polishing station106. The arrangement of the ECMP stations 106 and polishing stations 102on the apparatus 100 allow for the substrate 114 to be sequentiallyplated or polished by moving the substrate between stations while beingretained in the same polishing head 130.

To facilitate control of the polishing apparatus 100 and processesperformed thereon, a controller 140 comprising a central processing unit(CPU) 142, memory 144, and support circuits 146, is connected to thepolishing apparatus 100. The CPU 142 may be one of any form of computerprocessor that can be used in an industrial setting for controllingvarious drives and pressures. The memory 144 is connected to the CPU142. The memory 144, or computer-readable medium, may be one or more ofreadily available memory such as random access memory (RAM), read onlymemory (ROM), floppy disk, hard disk, or any other form of digitalstorage, local or remote. The support circuits 146 are connected to theCPU 142 for supporting the processor in a conventional manner. Thesecircuits include cache, power supplies, clock circuits, input/outputcircuitry, subsystems, and the like.

Power to operate the polishing apparatus 100 and/or the controller 140is provided by a power supply 150. Illustratively, the power supply 150is shown connected to multiple components of the polishing apparatus100, including the transfer station 110, the factory interface 120, theloading robot 116 and the controller 140. In other embodiments separatepower supplies are provided for two or more components of the polishingapparatus 100.

FIG. 2 depicts one embodiment of the electrochemical mechanicalpolishing (ECMP) station 102 of FIG. 1. Generally, the ECMP station 102comprises a polishing head 130 adapted to retain the substrate 214.Illustratively, the polishing head 130 is a cantilever mounted to acarousel 211 by a brace 237. The carousel 211 operates to rotate thepolishing head 130 to a position over various stations, including theECMP station 102. Examples of embodiments of polishing heads 130 thatmay be used with the polishing apparatus 102 described herein aredescribed in U.S. Pat. No. 6,024,630, issued Feb. 25, 2000 to Shendon,et al. One particular polishing head that may be adapted to be used is aTITAN HEAD™ wafer carrier, manufactured by Applied Materials, Inc.,located in Santa Clara, Calif.

The ECMP station 102 further includes a basin 202, an electrode 204,polishing article 205, a pad support disc 206 and a cover 208. In oneembodiment, the basin 202 is coupled to a base 207 of the polishingapparatus 102. The basin 202, the cover 208, and the disc 206 may bemovably disposed relative to the base 207. Accordingly, the basin 202,cover 208 and disc 206 may be axially moved toward the base 207 tofacilitate clearance of the polishing head 130 as the carousel 211indexes the substrate 214 between the ECMP 102 and other polishingstations (not shown).

The basin 202 generally defines a container or electrolyte-containingvolume 232 in which a conductive fluid such as an electrolyte 220 (shownin a reservoir 233) can be confined and in which the electrode 204,polishing article 205, and disc 206 are generally housed. Theelectrolyte 220 used in processing the substrate 214 canelectrochemically remove metals such as copper, aluminum, tungsten,gold, silver or other conductive materials. Accordingly, the basin 202can be a bowl-shaped member made of a plastic such as fluoropolymers,TEFLON®, PFA, PE, PES, or other materials that are compatible withelectroplating and electropolishing chemistries.

The basin 202 has a bottom 210 that includes an aperture 216 and a drain214. The aperture 216 is generally disposed in the center of the bottom210 and allows a shaft 212 to pass therethrough. A seal 218 is disposedbetween the aperture 216 and the shaft 212 and allows the shaft 212 torotate while preventing fluids disposed in the basin 202 from passingthrough the aperture 216. Rotation is imparted to the shaft 212 by amotor connected to a lower end of the shaft 212. The motor may be anactuator capable of rotating the shaft at a predefined speed or speeds.

At an upper end, the shaft carries the disc or pad support 206. The padsupport disc 206 provides a mounting surface for the polishing article205, which may be secured to the disc 206 by a clamping mechanism or anadhesive (such as a pressure sensitive adhesive). Although shownconnected to the shaft 212, in another embodiment, the disc 206 can besecured in the basin 202 using fasteners such as screws or otherfastening means, thereby eliminating the need for the shaft 212. Thedisc 206 can be spaced from the electrode 204 to provide a betterelectrolyte recirculation.

In one embodiment, the disc 206 may be made from a material compatiblewith the electrolyte 220 which would not detrimentally affect polishing.Illustratively, the disc 206 may be fabricated from a polymer, forexample fluoropolymers, PE, TEFLON®, PFA, PES, HDPE, UHMW or the like.In one embodiment, the disc 206 includes a plurality of perforations orchannels formed therein. The perforations are coupled to theperforations of the polishing article 205 which, cooperatively, definechannels 222 extending from a lower surface of the disc 206 to an uppersurface of the polishing article 205. The provision of the channels 222make the disc 206 and the polishing-article 205 generally permeable tothe electrolyte 220. The perforation size and density is selected toprovide uniform distribution of the electrolyte 220 through the disc 206to the substrate 214.

The polishing article 205 can be a pad, a web or a belt of material,which is compatible with the fluid environment and the processingspecifications. The polishing article 205 is positioned at an upper endof the basin 202 and supported on its lower surface by the disc 206. Inone embodiment, the polishing article 205 includes at least a partiallyconductive surface of a conductive material for contact with thesubstrate surface during processing. Accordingly, the polishing article205 may be a conductive polishing material or a composite of aconductive polishing material disposed in a conventional polishingmaterial. The conductive material may also be inserted between the disc206 and polishing article 205 with some conductive ends in contact withthe substrate during polishing. The conductive polishing materials andthe conventional polishing materials generally have mechanicalproperties which do not degrade under sustained electric fields and areresistant to degradation in acidic or basic electrolytes.

Because the polishing article 205 is at least partially conductive, thepolishing article 205 may act as an electrode in combination with thesubstrate during electrochemical processes. The electrode 204 is acounter-electrode to the polishing article 205 contacting a substratesurface. The electrode 204 may be an anode or cathode depending upon thepositive bias (anode) or negative bias (cathode) applied between theelectrode 204 and polishing article 205.

For example, depositing material from an electrolyte on the substratesurface, the electrode 204 acts as an anode and the substrate surfaceand/or polishing article 205 acts as a cathode. When removing materialfrom a substrate surface, such as by dissolution from an applied bias,the electrode 204 functions as a cathode and the substrate surfaceand/or polishing article 205 may act as an anode for the dissolutionprocess.

The electrode 204 is generally positioned between the disc 206 and thebottom 210 of the basin 202 where it may be immersed in the electrolyte220. The electrode 204 can be a plate-like member, a plate havingmultiple holes formed therethrough or a plurality of electrode piecesdisposed in a permeable membrame or container. A permeable membrane (notshown) may be disposed between the disc 206 and the electrode 204 toprevent particles or sludge from being released from the electrode 204into the electrolyte. The permeable membrane may also act as a filterand prevent gas evolution from the counter electrode from reaching thesubstrate during processing. Pores size and density of the permeablemembrane are defined in a way to optimize the process performances.

For electrochemical removal processes, such as anodic dissolution, theelectrode 204 may include a non-consumable electrode of a material otherthan the deposited material, such as platinum for copper dissolution.However, the electrode 204 can also be made of copper for copperpolishing, if preferred.

In operation, electrolyte 220 is flowed from a reservoir 233 into thevolume 232 via a nozzle 270. The electrolyte 220 is prevented fromoverflowing the volume 232 by a plurality of holes 234 disposed in askirt 254. The holes 234 generally provide a path through the cover 208for the electrolyte 220 exiting the volume 232 and flowing into thelower portion of the basin 202. At least a portion of the holes 234 aregenerally positioned between a lower surface 236 of the depression 258and the center portion 252. As the holes 234 are typically higher thanthe lower surface 236 of the depression 258, the electrolyte 220 fillsthe volume 232 and is thus brought into contact with the substrate 214and polishing article 205. Thus, the substrate 214 maintains contactwith the electrolyte 220 through the complete range of relative spacingbetween the cover 208 and the disc 206.

The electrolyte 220 collected in the basin 202 generally flows throughthe drain 214 disposed at the bottom 210 into the fluid delivery system272. The fluid delivery system 272 typically includes the reservoir 233and a pump 242. The electrolyte 220 flowing into the fluid deliverysystem 272 is collected in the reservoir 233. The pump 242 transfers theelectrolyte 220 from the reservoir 233 through a supply line 244 to thenozzle 270 where the electrolyte 220 recycled through the ECMP station102. A filter 240 is generally disposed between the reservoir 233 andthe nozzle 270 to remove particles and agglomerated material that may bepresent in the electrolyte 220.

Electrolyte solutions may include commercially available electrolytes.For example, in copper containing material removal, the electrolyte mayinclude sulfuric acid, sulfuric acid salt based electrolytes orphosphoric acid, phosphoric acid salt based electrolytes, such aspotassium phosphate (K₃PO₄), (NH₄)H₂PO₄, (NH₄)₂HPO₄, or combinationsthereof. The electrolyte may also contain derivatives of sulfuric acidbased electrolytes, such as copper sulfate, and derivatives ofphosphoric acid based electrolytes, such as copper phosphate.Electrolytes having perchloric acid-acetic acid solutions andderivatives thereof may also be used. Additionally, the inventioncontemplates using electrolyte compositions conventionally used inelectroplating or electropolishing processes, including conventionallyused electroplating or electropolishing additives, such as brighteners,chelating agents, and levelers among others. In one aspect of theelectrolyte solution, the electrolyte may have a concentration betweenabout 0.2 and about 1.2 Molar of the solution. Preferably, theelectrolyte is selected to react with metal but not with the underlyingmaterials, such as the dielectric.

During operation, a potential difference is applied between theelectrode 204 and the conductive polishing article 205, which acts asanother electrode of opposite polarity with respect to the electrode204. The substrate 214 being in direct contact with the conductivepolishing article 205 will then be at the same potential as theelectrode 205. In this manner, a bias may be applied to the substrate214 via conductive contact elements (described below) embedded in thepolishing article 205. Preferably, a current is also flowed through thesubstrate via the embedded conductive contact elements. The current loopmay be completed in the polishing station by transforming atomicsubstrate materials into ions in the electrolyte. Concurrent mechanicalpolishing of the substrate 214 is achieved by relative movement betweenthe substrate and the polishing article 205.

The provision of potential difference between the electrode 204 and thesubstrate 214 allows removal of conductive material, such ascopper-containing materials, formed on a substrate surface. Establishingthe potential difference may include the application of a voltage ofabout 15 volts or less to the substrate surface. A voltage between about0.1 volts and about 10 volts may be used to dissolve copper-containingmaterial from the substrate surface and into the electrolyte. Thepotential difference may also produce a current density between about0.1 milliamps/cm² and about 50 milliamps/cm², or between about 0.1 ampsto about 20 amps for a 200 mm substrate. Preferably, the embeddedconductive contact elements in the polishing article 205 have lowresistivity (less than 1 Ohm) and are capable of providing high current(greater than 1 amp and preferably between about 10 amps and 20 amps).

The signal provided by the power supply 150 to establish the potentialdifference and perform the anodic dissolution process may be varieddepending upon the requirements for removing material from the substratesurface. For example, a time varying anodic signal may be provided tothe conductive polishing article 205. The signal may also be applied byelectrical pulse modulation techniques. The electrical pulsemodification technique comprises applying a constant current density orvoltage over the substrate for a first time period, then applying aconstant reverse voltage over the substrate for a second time period,and repeating the first and second steps. For example, the electricalpulse modification technique may use a varying potential from betweenabout −0.1 volts and about −15 volts to between about 0.1 volts andabout 15 volts.

In one embodiment, conductive material, such as copper containingmaterial can be removed from at least a portion of the substrate surfaceat a rate of about 15,000 Å/min or less, such as between about 100 Å/minand about 15,000 Å/min. In one embodiment of the invention where thecopper material to be removed is less than 5,000 Å thick, the voltagemay be applied to the conductive polishing article 205 to provide aremoval rate between about 100 Å/min and about 5,000 Å/min.

Polishing Media: Structure

Particular embodiments of the polishing article 205 will now bedescribed with reference to FIGS. 3-14. It is understood that thefollowing embodiments are merely illustrative and persons skilled in theart will recognize other embodiments within the scope of the invention.

Referring first FIG. 3, a partial perspective view of one embodiment ofthe polishing article 205 is shown. In the illustrative embodiment, thepolishing article 205 generally includes an upper polishing surface 302having annular grooves 304 defined therein. However, in a preferredembodiment, the upper polishing surface 302 is smooth (i.e., withoutgrooves). In fact, in some embodiments, the polishing article 205 is noteven adapted for polishing (i.e., the polishing article 205 does nothave a polishing surface.) and serves primarily as a support body forcarrying embedded conductive contact elements (described below). Onesuch embodiment would be in an apparatus for plating. Accordingly, theterm “polishing” used in the context of the polishing article 205 ismerely for convenience of identifying a preferred embodiment.

Holes 306 defined in the polishing article 205 define the upper terminalends of the channels 222. A contact element 308 in the form of twistedwires traverses the distance between two adjacent holes 306. The contactelement 308 extends some distance over the upper polishing surface 302to form an arch. For simplicity, only a single contact element 308 isshown. However, the polishing article 205 may be equipped with anynumber of such contact elements 308. Further, in some embodiments, asingle contact element 308 traverses the distance between two or moreadjacent holes 306.

In one aspect, the contact element 308 provides limited friction whileaccommodating multidirectional movement of a substrate. That is, thecontact element 308 possesses sufficient flexibility to move in variousplanar directions, preferably all planar directions. In this manner, thecontact element 308 provides good and reliable electrical contact withminimal friction and scratches while polishing a substrate. Further, thewire contact element 308 of FIG. 3 is adaptable to face up or face downprocessing. In this regard, it is noted that while the ECMP station 102of FIG. 1 is configured for face down processing, face up processingsystems are well known and a detailed description of such systems is notneeded.

Referring now to FIG. 4, one embodiment of securing the contact element308 is shown. In particular, FIG. 4 shows a perspective cross-sectionalview of the polishing article 205, in which the polishing article 205generally comprises an upper polishing pad 402 and a lower support pad404. In one embodiment, the upper polishing pad 402 is made ofpolyurethane while the support pad 404 is made of polyetheretherketone(PEEK). The upper polishing pad 402 may be secured to the support pad404 by a pressure sensitive adhesive (PSA) or any other means ofaffixing the polishing pad 402 to the support pad 404. Collectively, theupper polishing pad 402 and the support pad 404 define a pad body.However, as used herein, a pad body may be any material which makes upat least a part of the polishing article 205 and may be one or morelayers of material. In one aspect, the support pad 404 provides supportfor both the polishing pad 402 (to achieve a desired degree offlexibility, conformance and/or rigidity) as well as an electricalcontact assembly described below. A portion of the upper polishing pad402 is removed to expose a portion of the underlying support pad 404. Assuch, the exposed portion of the support pad 404 is recessed below theupper polishing surface of the polishing pad 402 by a distance D.Inserts 406 (which may also referred to herein as hollow inserts,housings or hollow housings) are disposed through the support pad 404and define openings 410 to each receive an end 412A, 412B of the contactelement 308. The inserts 406 may be of any sufficiently conductivematerial. As such, the inserts 406 may be made of metal or may beplated/coated with a conductive material, for example. In a particularembodiment, the inserts 406 are made of, or are coated with, gold. Inthe illustrated embodiment, the inserts 406 are hollow; however, inother embodiments the inserts 406 are at least partially filled. Theends 412A, 412B of the contact element 308 are secured to the hollowinserts 406 with insulating members 414A, 414B, respectively. Theinsulating members 414A, 414B have a lower plug member 416A, 416B whichis sized to fit within the openings 410 and to ensure good contactbetween the inner surfaces of the inserts 406 and the ends 412A-B of thecontact element 308. At least one of the hollow inserts 406 is inelectrical contact with a wire 418 (or any other conducting element).Illustratively, engagement between the wire 418 and the hollow insert406 is secured by another insulating inserts 414C. The wire 418 isconnected to the power supply 150 (shown in FIG. 1). In this manner,current may be provided to the contact element 308. In the illustrativeembodiment, electrical contact between the wire 418 and the contactelement 308 is achieved via the hollow insert 406. In anotherembodiment, the wire 418 and the contact element 308 may be directlyconnected with one another.

In the embodiment described with respect to FIG. 4, the contact member308 forms an arch, a portion of which extends some height H above theupper surface of the polishing pad 402. In one embodiment, the height His between about 1 and 2 mm. More generally, the contact member 308 mayassume any geometric shape and height providing sufficient flexibilityin various directions. For example, in another embodiment, the contactelement 308 defines a loop, as shown in FIG. 5. In yet anotherembodiment, the contact element defines a partially twisted loop/arch aswill be described with reference to FIGS. 11 and 12 below.

FIG. 6 shows yet another embodiment for coupling current from the powersupply 150 to the contact element 308. In contrast to the embodimentsshown in FIGS. 4-5, a single insulating insert 414A is used to securethe contact element 308 in contact with the conductive hollow insert406. In this case, a portion of the contact element 308 is wound aboutthe outer surface of the insulating insert 414A, while the upper portionof the contact element 308 forms an arch extending some height over theupper polishing pad 402. In some embodiments, the contact element 308may be secured to the insulating insert 414A by threading a portion ofthe contact element 308 through a hole (not shown) formed in theinsulating insert 414. However, in any case, a portion of the contactelement 308 remains exposed to allow electrical contact with theelectrically conductive hollow insert 406 when the insulating insert414A is disposed in the opening 410.

FIGS. 7A and 7B show yet another embodiment for coupling current fromthe power supply 150 to contact elements 308. In particular, FIG. 7Ashows a top view and FIG. 7B shows a side cross-sectional view,respectively, of a contact element carrier 700. In FIG. 7B, the contactelement carrier 700 is shown disposed in a pad body comprising an upperpad 402 and a lower support pad 404. As best seen in FIG. 7A, thecontact element carrier 700 is a generally cross-shaped membercomprising a body 702 and a plurality of arms 704A-D extendingtherefrom. The particular shape and number of arms 704 shown in FIG. 7Ais merely illustrative; in other embodiments, any number of arms 704 maybe provided. Each arm 704 has a hole 706A-D extending therethrough. Asshown in FIG. 7B, the holes (706A and 706C shown) extend through theheight of the respective arms. However, in other embodiments the holes706 extend through only a part of the arms. In any case, the holes 706are sized to receive and retain an end of a contact member 308. Theother end of the contact member 308 is disposed against an inner surfaceof a hollow housing 708 and retained in this position by an insulatingmember 710A. The insulating member 710A has a lower plug member 712Awhich is sized to fit within an opening 714 of the hollow housing 708and to ensure adequate contact between the inner surfaces of the hollowhousings 708 and the ends of the contact elements 308A-D. The hollowhousing 708 is in electrical contact with a wire 716 (or any otherconducting element), which is connected to the power supply 150.Illustratively, engagement between the wire 716 and the hollow housing708 is secured by another insulating insert 710B. The wire 716 isconnected to the power supply 150 (shown in FIG. 1). In this manner,current may be provided to the contact elements 308A-D. In theillustrative embodiment, electrical contact between the wire 716 and thecontact elements 308A-D is achieved via the hollow housing 708. Inanother embodiment, the wire 716 and the contact elements 308A-D may bedirectly connected with one another.

FIG. 8A shows yet another embodiment for coupling current from the powersupply 150 to the contact element 308. In general, the contact element308 is a wire (or twisted strands of wire) wound about one or moreelongated conducting members 802A-B. Illustratively, two elongatedconducting members 802A, 802B are shown. In one aspect, the bottomconducting member 802B facilitates wire assembly (e.g., by press-fittingor gluing into a U-shaped conduit 804) and the upper conducting member802A is a sacrificial element which may prevent electrochemicaldissolution of the wires 308. In one embodiment, the elongatedconducting members 802 are cylindrical members (such as tubes or rods)formed of, or coated with, conducting material (such as gold). However,more generally, the elongated conducting members 802 may be of anysuitable geometry according to the purpose described herein. Wherecylindrical members are used, the elongated conducting members 802 mayhave a diameter D between about 0.125 and 0.5 inches, for example. Inone embodiment, the diameter of the upper elongated conducting member802A is different from the lower elongated conducting member 802B. Theelongated conducting members 802 are preferably in contact with oneanother along a substantial portion of their lengths. Alternatively,electrical contact between the elongated conducting members 802 is madevia the contact element 308.

At least one of the elongated conducting members 802 is at leastpartially disposed in, and in contact with, a U-shaped conduit 804,which is also electrically conductive and coupled to the power source150. The U-shaped conduit 804 is disposed in a channel 806 formed withina pad body 808 of the polishing article 205, where the pad body 808 maycomprise one or more layers of pad material.

In one embodiment, the U-shaped conduit 804 may be seated in acorrespondingly shaped U-shaped conduit. Such an arrangement mayfacilitate quick and easy replacement of the assembly comprising theU-shaped conduit 804, the elongated conducting members 802 and thecontact element 308.

As noted above, the contact element 308 is a wire (or twisted strands ofwire) wound about one or more of the elongated conducting members 802.Even where twisted strands of wire are used, the conducting element 308may form a singular (i.e., unbroken) piece of material which assumes aspiraling configuration around the elongated conducting members 802. Inone embodiment, the contact element 308 is wound about each elongatedconducting member 802 with an equal number of turns. In anotherembodiment, the number of turns around the bottom elongated conductingmember 802B is greater than the number of turns around the upperelongated conducting member 802A, as a shown in FIG. 8B (which shows anexploded view of the elongated conducting members 802 relative to theU-shaped conduit 804). In any case, a portion of the contact element 308extends some height H above the upper polishing surface of the pad body808. Further, the respective adjacent arch portions of the contactelement extending above the upper polishing surface of the pad body 808are separated from one another by a width W. In one embodiment, theheight H is between about 0.040 inches and 0.125 inches, and the width Wis between about 0.040 inches and 1 inch.

Referring to FIG. 9, another embodiment for coupling current from thepower supply 150 to the contact element 308 is shown (in an explodedview). For simplicity, like numerals are used to identify likecomponents of FIGS. 8A and 8B. In general, the contact element 308 is acoating or sheet wrapped at least partially about the one or moreelongated conducting members 802 (illustratively two shown). In oneembodiment, the coating is a nylon fabric comprising a conductingportion. For example, the conducting portion can be a gold coatingdisposed on the nylon fabric.

The number, placement and geometry of the current conducting assemblyshown in FIGS. 8-9 may vary according to application. In one embodiment,a single U-shaped conduit 804 with one or more elongated conductingmembers 802 may be sufficient. In one embodiment, a U-shaped conduit 804traverses substantially the entire radius of the polishing article 205.In alternative embodiment, a U-shaped conduit 804 traverses only aportion of the radius of the polishing article 205. In yet anotherembodiment, one or more U-shaped conduits 804 traverse the entire radiusof the polishing article 205, while one or more U-shaped conduits 804traverse only a portion of the radius. In still another embodiment, aU-shaped conduit 804 traverses a distance greater than the radius of thepolishing article 205, such as the entire diameter of the polishingarticle 205.

In one embodiment, the U-shaped conduit 804 and/or the elongatedconducting members 802 (or any other structure or material in thevicinity of the contact elements 308) are at least partially formed asacrificial material. A sacrificial material is any material which isconsumed during electrochemical processing, in order to minimize thedamage to the contact elements 308. For example, in one embodiment thecontact element 308 is a gold-containing material, while the sacrificialmaterial is copper. It is believed that the presence of such asacrificial material in the vicinity of the contact element 308 reducesthe potential damage to the contact element 308 because negative ions,which would otherwise attacked the gold-containing material, are used toetch the sacrificial material.

In another embodiment, the lifetime of the contact elements 308 (i.e.,the time period during which the contact elements 308 are usable toachieve a desired result) is increased by increasing the availablematerial (along some portion of the contact element 308) that comes intocontact with a substrate. One such embodiment is a shown in FIG. 10.Generally, the embodiment shown in FIG. 10 is substantially the same asthat shown in FIG. 8. However, in contrast to previous embodiments, thecontact elements 308 are now equipped with nodules 1002. Although eachcontact element 308 is shown equipped with only a single nodule 1002,two or more nodules 1002 may be formed on each contact element 308.

In general, the nodules 1002 are portions disposed on and/or supportedby wire portions 1004 of the contact element 308. As such, the wireportions 1004 may also be referred to herein as support portions orsupport members for the nodules 1002. In one embodiment, the nodules1002 are relatively enlarged portions compared to a greatest diameter ofthe wire portions 1004. However, the nodules 1002 may also be ofsubstantially the same size but made of a different material. Forexample, the nodules 1002 may be wire segments made of a first materialplaced between two ends of the wire portions 1004 made of a secondmaterial, but having substantially the same diameter. The nodules may beformed on the contact elements 308 using any number of techniquesincluding, for example, welding.

Illustratively, the nodules 1002 are substantially spherical membersdisposed at an upper and of the contact elements 308. In one aspect, asubstantially smooth and spherical shape may be advantageous inpreventing damage to the contacting substrates being polished. However,more generally, any geometric shape of the nodules 1002 may be used toadvantage. Further, since the nodules 1002 are positioned to contact thesubstrate being polished, wear on the wire portion 1004 of the contactmembers 308 may be reduced.

In one embodiment, the nodules 1002 and the wire portion 1004 of thecontact elements 308 are of the same material. For example, the nodules1002 and the wire portion 1004 may be gold or gold plated. In anotherembodiment, the nodules 1002 and the wire portion 1004 are of differentmaterials. For example, the nodules 1002 may comprise gold while thewire portion 1004 is copper.

In one aspect, the provision of nodules 1002 provide bulk materialhaving a greater longevity (wear resistance) than the wire portion 1004,which provides a desirable degree flexibility. In addition, the nodules1002 may be highly polished to reduce the probability of scratching thesubstrate being polished.

It should be understood that any of the embodiments of the contactelement 308 disclosed herein may comprise nodules such as those shown inFIG. 10.

FIG. 11 shows another embodiment of a contact element carrier and wirecontact element 308. In particular, FIG. 11 shows a perspective view ofa contact element carrier 1100. The contact element carrier 1100 is agenerally disk shaped member having the wire contact element 308disposed thereon. A wire 1104 connects the wire element to the powersupply 150. The wire contact element 308 is arranged as a partiallytwisted loop, or arch. This orientation may be achieved by first formingan arch with the wire element 308 (such as is shown in FIG. 4) and thentwisting the wire element approximately 90 degrees about it central axis(i.e., the axis extending perpendicularly from the upper surface of thecontact element carrier 1102 and through the center of the arch wireelement. The resulting partially twisted loop/arch allows forbidirectional flexibility in two planar directions, shown by the arrows.

The construction of the contact element carrier 1100 may be understoodwith reference to the exploded view shown in FIG. 12. In general, thecontact element carrier 1100 comprises an upper isolating disk 1106, alower isolating disk 1108 and a conductive disk 1110. The conductivedisk 1110 is disposed on the bottom isolating disk 1108 and may besecured thereto by any appropriate means including, for example, apressure sensitive adhesive (PSA). The wire contact element 308 in theform of an arch is disposed on the conductive disk 1110. The conductivewire 1104 is connected to the wire contact element 308 in a manner thatensures good electrical contact. A slit 1112 formed in the upperisolating disk 1106 accommodates the wire contact element 308, which isdisposed therethrough in the finished product. The upper isolating disk1106, lower isolating disk 1108 and conductive disk 1110 may be securedto one another by adhesive applied to the backs of the respectivesurfaces.

The upper and lower isolating disks 1106, 1108 may be made of anyinsulating material including, for example, plastic while the conductivedisk 1110 may be made of any electrically conductive material suchcopper foil. The wire contact element 308 may be made of anyelectrically conductive material, preferably a noble metal such as gold,platinum or titanium. In each case, the components of the contactelement carrier 1100 and the wire element 308 may be composite materialsor may be coated with the appropriate material.

In each of the foregoing embodiments described with respect to FIGS.4-12, the contact element 308 may comprise a plurality of conductingelements. For example, in one embodiment the contact element 308comprises a plurality of wire strands or filaments, which may betwisted. In a particular embodiment, each contact element 308 comprisesM number of wires with N number of twists per inch, where M is betweenabout 6 and 12, and N is between about 0.5 and 5 inches. Further, thewires that make up the contact element 308 may be gold or gold plated.In one embodiment, the wires are a gold alloy (such as AW14 or AW8) andmay have a diameter of 1.3-3 mils.

In another embodiment, the polishing article 205 is equipped withrolling contact elements. The rolling contact elements are configurablefor wafer facedown and wafer faceup processing. A simplified schematiccross sectional side view of an embodiment of the polishing article 205with a rolling contact element configured for wafer face up processingis shown in FIG. 13. In general, the polishing article 205 comprises apolishing pad 1302 and a support pad 1304, which may be attached to oneanother by a pressure sensitive adhesive (PSA), for example. Thepolishing pad 1302 may be made of polyurethane. The support pad 1304 maybe made of PEEK. An opening 1306 is formed in the polishing pad 1302 andthe support pad 1304. The opening 1306 is shaped to accommodate arolling contact element 1308. The rolling contact element 1308 isdisposed within the opening 1306 in a manner that allows rotation aboutat least one axis 1316, where the axis 1316 is parallel to a plane of asubstrate 1313. As such, the geometry of the rolling contact element1308 may be cylindrical, spherical, conical, frustroconical, etc. Inoperation, the rotation of the substrate 1313 (e.g., in the direction ofthe arrow 1314) causes a corresponding rotation of the rolling contactelement 1308, as represented by the arrow 1318.

In one embodiment, the rolling contact element 1308 is “floating” withinthe opening 1306. For example, the rolling contact element 1308 may berotatably suspended on a spring-loaded axle axially disposed on the axis1316. In this manner, the rolling contact element 1308 may be urgedupwardly through the opening 1306 when brought into contact with thesubstrate 1313. Gravity and/or a spring bias ensures a good and reliablecontact between the rolling contact element 1308 and the substrate 1313.To prevent the rolling contact element 1308 from falling out of theopening 1306 when the substrate 1313 is not present, any variety ofmethods and mechanisms may be used to advantage. Illustrativeembodiments are described below.

At least the outer surface of the rolling contact element 1308 iselectrically conductive so that a current (generated by the power supply150) may be flowed through the electrically conductive portion of therolling contact element 1308. In the illustrative embodiment, thecurrent is communicated from the power supply 150 to the rolling contactelement 1308 via wire elements 1312A-B (two are shown, but any number iscontemplated). More particularly, the power supply 150 may be coupled towire element holders 1310A-B, each of which has a respective wireelement 1312A-B connected thereto. Preferably, either or both the wireelements 1312 and the wire element holders 1310 comprise a noble metal,such as gold. In one embodiment, the noble metal may be a platingdisposed over the wire elements and/or the wire element holders.

In one embodiment, the wire element holders are elongated rods spacedsufficiently far enough apart from one another to allow positioning ofthe rolling contact element 1308 therebetween. In such a configuration,a plurality of individual rolling contact elements 1308 may be disposedbetween a pair of wire element holders 1310. Further, a plurality ofwire element holder pairs may be disposed within the polishing article205. For example, N pairs of wire element holders 1310 may be radiallydisposed on the polishing article 205, with each pair of wire elementholders accommodating M rolling contact elements 1308, where N and M areinteger numbers. In a particular embodiment, N and M equal eight (8).

Referring now to FIG. 14, a facedown processing configuration of thepolishing article 205 is shown in schematic. For brevity and simplicity,like numerals are used to indicate the same or similar componentsdescribed above with respect to FIG. 13, regardless of differences inrelative orientation and/or position. In the embodiment of FIG. 14, therolling contact element 1308 is disposed in a fluid flow channel 1402,extending through the support pad 1304 and the polishing pad 1302.Downward travel of the rotating contact element 1308 is restricted bythe provision of the wire element holders 1310A-B, which are spacedapart at a distance less than a diameter of the rolling contact element1308. The wire element holders 1310 are disposed within the fluid flowchannel 1402, thereby preventing the rotating contact element 1308 frominadvertently dropping out of the bottom of the fluid flow channel 1402.

Prior to initiating polishing of the substrate 1313, the rotatingcontact element 1308 may be (by operation of gravity) recessed below theplane of the upper polishing surface of the pad 1308. In order to bringthe rotating contact element 1308 into contact with the substrate 1313,a fluid (e.g., electrolyte or a gas) is flowed into the fluid flowchannel 1402, as indicated by the arrow 1404. In one embodiment, thefluid flow channel 1402 creates fluid flow resistance resulting in apressure drop across the rotating contact element 1308, which providesthe necessary force to lift the rotating contact element 1308 in araised processing position. FIG. 14 shows the rotating contact element1308 in the raised processing position (i.e., in contact with thesubstrate 1313). The particular lifting force applied to the rotatingcontact element 1308 may be controlled by varying the fluid pressure.Generally, increasing fluid pressure include the lifting force, whiledecreasing fluid pressure will decrease the lifting force. Note that, inthe raised processing position, the wire elements 1312 are sufficientlyflexible to maintain good electrical contact with the rotating contactelement 1308, without substantially inhibiting the rotation thereof.

In addition to fluid levitation, the rotating contact element 1308 mayalso be placed in the raised processing position by magnetic orelectromagnetic force. For example, a permanent magnet may be embeddedin the rotating contact element 1308 and an electromagnet may be placedon one side of the substrate 1313. Depending on the location of theelectromagnet, the polarity of the electromagnets may be eitherattractive or repulsive with respect to the permanent magnet embedded inthe rotating contact element 1308. For example, if the electromagnet isdisposed in the fluid flow channel 1402 below the rotating contactelement 1308, then the polarity of the electromagnet is selected to berepulsive with respect to permanent magnet in order to magnetically biasthe rotating contact element 1308 upward into contact with thesubstrate. In one embodiment, the wire element holders 1310A-B areelectromagnets. Alternatively, the electromagnet may be disposed overthe substrate (e.g., in the carrier head of the polisher), in which casethe polarity of the electromagnet is selected to be attractive withrespect to permanent magnet in order to magnetically bias the rotatingcontact element 1308 upward into contact with the substrate.

As described above, it is contemplated that a plurality of rollingcontact elements 1308 may be used and brought into contact with thesubstrate 1313 during polishing. However, the provision of additionalrolling contact elements which do not contact the substrate 1313 duringpolishing is also contemplated. For example, two or more rolling contactelements 1308 may be stacked on top of one another (i.e., in the planeof the FIGS. 13 and 14). One such embodiment is shown in FIG. 15. Inparticular, FIG. 15 shows a schematic side view of an embodiment of thepolishing article 205 equipped with three rolling contact elements 1508.

In general, FIG. 15 shows a pad 1502 disposed on a support pad 1504 anda contact assembly 1500 disposed at least partially within the supportpad. The contact assembly 1500 generally includes a housing 1520 andthree rolling contact elements 1508A-C residing within the housing 1520.The travel of the rolling contact elements 1508A-C within the housing1520 may be limited at one end by a diametrically restricted opening(not shown). The travel of the ball is limited at another end by aheight adjustment mechanism 1530. In particular, the bottom rollingcontact element 1508A is shown resting on (in contact with) a heightadjustment arm 1532. The height adjustment arm 1532, in turn, issupported by an adjustor 1534 disposed in a bore 1536 defined in thesupport pad 1504. In one embodiment, the adjustor is a threaded memberhaving threads engaged with counter-threads formed on the inner surfacewhich forms the bore. The height adjustment arm 1532 carries a rollerelement support pad 1538 at a distal end and on which the bottom rollercontact element 1508A rests. In one embodiment, the power supply 150 iscoupled to the pad 1538. In this manner, the current may be applied tothe bottom rotating contact element 1508A and communicated to the toprotating contact element 1508C (i.e., the rotating contact element incontact with the substrate) via any intermediate rotating contactelements (e.g., the middle rotating contact element 1508B). In anotherembodiment, the power supply 150 is coupled to the housing 1520. In yetanother embodiment, current may be coupled from the power supply 150 tothe one or more of the rotating contact elements 1508A-B via a wireelement (not shown).

Referring now to FIG. 16, a perspective view and a side cross-sectionalview, respectively, of another embodiment of the polishing article 205shown. In general, the polishing article 205 comprises an upperpolishing pad 1602 and a lower support pad 1604, which may be attachedto one another by a pressure sensitive adhesive (PSA), for example. Theupper polishing pad 1602 may be made of polyurethane. The lower supportpad 1604 may be made of PEEK. A recess 1606 is formed in the upperpolishing pad 1602 and the support pad 1604. Illustratively, the recess1606 is substantially rectangular in shape. More generally, the recess1606 may be any shape sized to accommodate a roller bearing contactassembly 1600. As best seen in FIG. 17, the roller bearing contactassembly 1600 is disposed in the recess 1606 such that the upper exposedsurface of the roller bearing contact assembly 1600 is substantiallycoplanar with the upper polishing surface of the upper polishing pad1602. However, the position of the roller bearing contact assembly 1600allows sufficient contact to be made with a substrate being polished.Accordingly, the upper surface of the roller bearing contact assembly1600 may be some height slightly above the upper polishing surface ofthe upper polishing pad 1602. Further, a lower surface of the rollerbearing contact assembly 1600 has a clearance with respect to a floor1608 of the recess 1606.

In the illustrated embodiment, the roller bearing contact assembly 1600is suspended over the floor 1708 by a pair of ball bearing assemblies1712A-B, one disposed at either end of the roller bearing contactassembly 1600. The ball bearing assemblies 1712 are disposed against thelower pad support 1604 and each receives an end of an axle 1714.

Referring still to FIG. 17, the roller bearing contact assembly 1600 isshown comprising a plurality of contact elements 1708 rotatably disposedon the axle 1714. Specifically, the contact elements 1708 aredisk-shaped members rotating about their central axes (along which theaxle 1714 is disposed). More generally, the contact elements 1708 may beany shape capable of rotating on the axle 1714. For example, in oneembodiment, the contact elements 1708 are conical or frustroconicalshaped members, where the contact elements 1708 rotating about the axisof symmetry. In the latter embodiment, the taper angle of the contactelements 1708 may be adjusted to adjust for changing linear speed withincreasing radius on an orbital polisher. Specifically, the contactelements 1708 may have an increasing diameter with the increasing radiusof the polishing pad. In another embodiment, the contact elements 1708are balls. The embodiments of the latter geometry (i.e., balls) aredescribed below.

In at least one embodiment, the contact elements 1708 are rigidlysecured to the axle 1714, and rotation of the contact elements 1708 isachieved by rotation of the axle 1714. In one embodiment, the contactelements 1708 may be separated from one another by washers, enlargedportions of the axle or any other feature, component or mechanismallowing separate rotation of the contact elements 1708.

Illustratively, the roller bearing contact assembly 1600 is showncomprising fourteen contact elements 1708. However, any number ofcontact elements 1708 may be used. Further, each individual contactelement 1708 may be of a different width (W). In one embodiment, thenumber and width of the contact elements 1708 may be selected accordingto their respective radial position on the polishing article 205. Inparticular, the number and width of the contact elements 1708 may beselected to accommodate the difference in rotational velocity of contactelements at different radial locations. For example, in one embodiment,the number of contact members 1708 per unit length may increase whiletheir width decreases with increasing radius of the polishing article205.

Current is provided to the roller bearing contact assembly 1600 via thepower supply 150. In one embodiment, the power supply 150 is connectedto the axle 1714. As such, to ensure adequate electrical conductivity,the axle 1714 and the contact members 1708 are preferably made of ametal. In one embodiment, the contact members 1708 are gold or aregold-plated. In a particular embodiment, the contact members 1708comprise a stainless steel core plated with gold. In another embodiment,the contact members 1708 comprise a non-conducting core (e.g., a nyloncore) coated with a conducting serial (e.g., gold or some other noblemetal).

Of course, other methods and configurations for electrically couplingthe power supply with the contact members 1708 are possible. Forexample, in one embodiment, a current is provided for the power supply150 via gold wire contacts located on a backside of the roller bearingcontact assembly 1600.

Referring again to FIG. 16, the roller bearing contact assembly 1600 isgenerally disposed radially from a central portion of the polishingarticle 205. Illustratively, only one roller bearing contact assembly1600 is shown disposed in the polishing article 205. However, it iscontemplated that any number of roller bearing contact assemblies may beused. Further, along any given radial line, two or more separate rollerbearing contact assemblies may be provided. Each separate roller bearingcontact assembly may have one or more contact elements 1708. In anycase, the roller bearing contact assembly 1600 is oriented to allow thecontact elements 1708 to rotate relative to a substrate brought intocontact with the contact elements 1708.

In some cases, it may be desirable to adjust the position of the rollerbearing contact assembly 1600. One position adjustment mechanism isshown in FIGS. 18A-B. In particular, FIG. 18A shows a sidecross-sectional view of a pair of position adjustment mechanisms 1820A-B(collectively the position adjustment mechanisms 1820) taken along theaxis of the axle 1714, while FIG. 18B shows an elevation of the positionadjustment mechanism 1820B taken along the section lines 18B-18B. Ingeneral, the position adjustment mechanisms 1820 each comprise a ballbearing assembly 1712A-B for receiving one end of the axle 1714, therebyallowing the axle 1714 to rotate freely about its longitudinal axis.Particular aspects of the ball bearing assemblies 1712A-B can best bedescribed with reference to FIG. 18B. Although FIG. 18B shows only oneball bearing assembly 1712B (i.e., the ball bearing assembly 1712B), itis understood that the ball bearing assembly 1712A is substantially thesame. The ball bearing assembly 1712B is secured by a pair of fasteners1824. In particular, the fasteners 1824 extend at least partially intothe lower support pad 1604. To this end, the fasteners 1824 may havethreaded portions at their respective ends. The shafts 1826 of thefasteners 1824 are of sufficient length to allow the ball bearingassembly 1712B a degree of travel along the shafts 1826. Travel of theball bearing assembly 1712B is limited at one end by the lower supportpad 1604 and at another end by the heads 1828 of the fasteners 1824.

In one embodiment, one or more biasing members are provided to urge theball bearing assemblies 1712A-B in a particular direction.Illustratively, FIG. 18B shows three biasing members 1830A-C. However,it is understood that any number of biasing members may be used toadvantage. With reference to FIG. 18B, the fasteners 1824 each carry abiasing member 1830A-B (collectively, the biasing members 1830). Inparticular, the biasing members 1830 are springs wound about a portionof the shafts 1826 of the respective fasteners 1824. Further, thebiasing members 1830 are disposed between the ball bearing assembly1712B and the lower support pad 1604. In this configuration, the biasingmembers 1830 urge the ball bearing assembly 1712B upwards. The highestposition of the ball bearing housing 1822 is reached when the ballbearing housing 1822 contacts the lower surface of the fastener heads1828. In one embodiment, a portion of the contact elements 1708 extendsa height slightly above the polishing surface of the upper polishing pad1602 when the ball bearing housing 1822 reaches its highest position.The particular height of the contact elements 1708 over the polishingsurface can be changed by adjusting the fasteners 1824 (e.g., screwingthe fasteners into or out of the lower support pad 1824).

The position adjustment mechanism 1820 is further shown comprising abiasing member 1832 disposed between the ball bearing housing 1822, thelower support pad 1604 and the fasteners 1824. Illustratively, thebiasing member 1832 is a spring disposed at least partially in a recess1834 formed in the lower support pad 1604. In one aspect, the recess1834 may provide a degree of stability to the biasing member 1832. Atits other end, the biasing member 1832 contacts the lower surface of theball bearing housing 1822. In this configuration, the biasing member1832 urges the ball bearing housing upward, thereby producingsubstantially the same effect as the biasing members 1830. Again, thehighest position and degree of freedom of the ball bearing housing 1822can be set by adjusting the fasteners 1824.

In operation, a substrate to be polished is brought into contact withthe polishing surface of the upper polishing pad 1602. If contact ismade between the substrate and the roller bearing contact assembly 1600(i.e., the contact elements 1708), a sufficient resulting force maycompress the biasing members 1830, 1832, if any such biasing members areprovided in the particular configuration being used. As a result, theroller bearing contact assembly 1600 is depressed. However, theprovision of the biasing members 1830, 1832 ensures a continuingpressure of the contact elements 1708 against the lower surface of thesubstrate. In addition, the contact elements 1708 roll over the lowersurface of the substrate, thereby reducing friction between the lowersurface of the substrate and the contact elements 1708.

During an electrochemical mechanical polishing operation, electrolyte isprovided to the surface of the substrate being polished. To this end,electrolyte may be deposited from a fluid delivery arm, for example,onto the polishing surface of the polishing article 205. In anotherembodiment, fluid is delivered into the recess 1706 via one or morefluid delivery channels (not shown) formed in the support pad 1604. Withsuch a fluid delivery configuration, and where the roller bearingcontact assembly 1600 is oriented for facedown processing and is infloating suspension (i.e., resting on biasing members, such as springs1830A-B and 1832), the fluid may provide enough pressure to urge theroller bearing contact assembly 1600 upward and in contact with thesubstrate.

Referring now to FIG. 19, a perspective view of an embodiment of thepolishing article 205 is shown in which roller contact assemblies areembedded therein. In general, the polishing article 205 comprises anupper polishing pad 1902 and a lower support pad 1904, which may beattached to one another by a pressure sensitive adhesive (PSA), forexample. In the present embodiment, the polishing article 205 isequipped with one or more rotating member assemblies (three shown).Illustratively, the roller contact assemblies are ball bearing contactassemblies 1900. For purposes of illustration, three ball bearingcontact assemblies 1900 are shown. However, any number of ball bearingcontact assemblies 1900 may be used to advantage in other embodiments.Further, in FIG. 19, the ball bearing contact assemblies 1900 arearranged in a radial line. In one embodiment, the polishing article 205may be equipped with a single radial line of ball bearing contactassemblies 1900. In such an arrangement, electrochemical mechanicalpolishing may be restricted to a particular area of the polishingarticle 205. However, any variety of other geometric arrangements iscontemplated. For example, a plurality of ball bearing contactassemblies 1900 may be uniformly distributed over the polishing surfaceof the upper polishing pad 1902. In another embodiment, the polishingarticle 205 may be equipped with a series of radial lines of ballbearing contact assemblies 1900.

Referring now to FIG. 20, a side cross-sectional view of a ball bearingcontact assembly 1900 is shown. The ball bearing contact assembly 1900generally includes a housing 2006, a current-conducting ball 2008 and acontact plate 2010. The housing 2006 is a generally cylindrical membersubstantially disposed in the lower support pad 1904. Threads 2012carried on outer surface of the housing 2006 engage counter-threads 2014which may be disposed on the support pad 1904 itself or on a threadedmember disposed between the support pad 1904 and the housing 2006. Inany case, the provision of the threads 2004 and the counter-threads 2014facilitate securing the housing 2006 in, and removing the housing 2006from, the support pad 1904. In one embodiment, the housing 2006 is madeof DELRIN®.

The housing 2006 forms a cavity 2018 which is generally sized toaccommodate the ball 2008. In particular, a degree of rotation of theball 2008 within the cavity 2018 is tolerated. To this end, a diameter(D1) of the ball 2008 is sized slightly smaller than a diameter (D2) ofthe housing 2006. As a result, when the ball 2008 is laterally centeredwithin the housing 2006, an annular gap 2016 exists between the mostproximate surfaces of the housing 2006 and the ball 2008.

The movement of the ball 2008 within the cavity 2018 is restricted atone end by a ball seat 2020 and at another end by a set screw 2022. Theball seat 2020 is a generally tapered surface formed at an upper end ofthe housing 2006. In particular, the ball seat 2020 tapers inwardly toform a restricted opening 2023 having a diameter (D3) smaller than thediameter (D1) of the ball 2008. Accordingly, the ball 2008 may travelaxially upward until engaging the ball seat 2020. The position of theball 2008 at its upper limit of travel is illustrated by the dashedlines 2008″.

The set screw 2022, which confines the ball 2008 at its lower limit, isthreadedly disposed in the contact plate 2010. In one embodiment, theset screw 2022 is a nylon member having threads on its outer surface.The set screw 2022 operates as a position adjustment mechanism which maybe extended or retracted to determine the limit of travel of the ball2008 within the cavity 2018. In one embodiment, the set screw 2022 ispositioned so that some degree of axial and rotational movement of theball 2008 is possible. In any case, it will be appreciated that the setscrew 2022 is merely illustrative of one adjustment mechanism. Personsskilled in the art will recognize that any variety of adjustmentmechanisms can be used to advantage.

In one embodiment, the contact plate 2010 is sized to be pressure fittedwithin the housing 2006. However, is understood that the contact plate2010 may be secured to the housing 2006 by other means, such as byfasteners, adhesives or the like. In addition to carrying the set screw2022, the contact plate 2010 carries a plug 2024. The plug 2024 may bemade of any material, such as rubber or some other elastomer, andsecures a contact element 2026 with respect to the contact plate 2010,to ensure electrical contact therebetween. The contact element 2026 maybe, for example, a wire or other flexible element capable of maintainingelectrical contact with the ball 2008 regardless of the particularposition of the ball 2008 within the cavity 2018. Although only onecontact element 2026 is shown, any number may be provided. For example,in one embodiment three contact element 2026 are positioned equidistant(i.e., 120 degrees) from one another.

In general, the ball 2008, the contact plate 2010, the contact element2026 are all current-conducting members. As such, these members may bemade of conducting materials such as metal. In a particular embodiment,the ball 2008 is a plastic or steel core plated with gold. In anotherembodiment, the ball 2008 is solid gold. Further, either or both thecontact plate 2010 and the contact element 2026 may include gold. In anycase, where each of the elements is conductive, the contact plate 2010is connected to the power supply 150 to provide a current to the contactelement 2026 and the ball 2008.

The contact plate 2010 also forms a fluid port 2028. The fluid port 2028allows fluid to flow from an exterior region (e.g., from the channelsformed in the pad support disk 206, i.e., platen) into the cavity 2018.In general, the fluid port 2028 may be sized according to a desiredfluid pressure and flow rate. In another embodiment, a valve may bedisposed in the fluid port 2028 to facilitate control over fluid flowthrough the fluid port 2028.

In operation, a substrate to be polished is brought into contact withthe upper surface of the polishing pad 1902. The position of lowersurface of the substrate is illustrated by the plane 2030, which issubstantially coplanar with the upper surface of the polishing pad 1902.Fluid (e.g., electrolyte) is then flowed through the fluid port 2028 toprovide a pressure sufficient to lift the ball 2008 from the set screw2022. In particular, the fluid flow around the ball 2008 creates apressure drop across the ball 2008, which lifts the ball 2008. In oneaspect, the provision of the pressure drop in this manner achieves africtionless, or substantially friction-reduced (relative to the innersurface of the housing 2006), environment for the ball 2008. Whensufficient pressure is available, the ball 2008 is brought intoengagement with the lower surface of the substrate. The position of theball 2008 while engaging the lower surface of the substrate isrepresented by the dashed lines 2008′. Note that, in this position, theupper surface of the housing 2006 is recessed below the plane 2030 whilea portion of the ball 2008 extends over the upper surface of the housing2006, thereby ensuring adequate contact between the ball 2008 and thesubstrate. Further, in this position, fluid flow is permitted around theball 2008 and through the upper opening 2023 of the housing 2006. Eitheror both the substrate and the pad 1902 may be actuated (e.g., rotated)to provide relative movement between the substrate and the pad. Duringsuch relative movement electrical contact between the ball 2008 and thesubstrate is maintained, while damage to the substrate and/or ball (dueto their relative movement) is mitigated because the ball 2008 is ableto rotate within the cavity 2018. In one aspect, fluid flow between theinner surface of the housing 2006 and the outer surface of the ball 2008establishes a fluid bearing, thereby facilitating rotation of the ball2008 within the cavity 2018.

In one embodiment, the ball bearing contact assembly 1900 may be usedfor wafer face down processing, as described above. That is, in facedown processing the ball bearing contact assembly 1900 is oriented suchthat the ball 2008 experiences a gravitational force F_(G1) which urgesthe ball 2008 downward toward the set screw 2022. Fluid flow (pressuredrop) provides the necessary lifting force to engage the ball 2008 withthe substrate. In an alternative embodiment, the ball bearing contactassembly 1900 may be used for face up processing. In face up processing,the ball 2008 experiences a gravitational force F_(G2) which urges theball 2008 toward the ball seat 2020 providing reliable electricalcontact of the ball 2008 and substrate (without the assistance of fluidflow induced pressure).

In wafer face down processing the ball bearing contact assembly 1900 maybe used as a pressure regulator. For example, the ball bearing contactassembly 1900 may be inserted in reversed position (ball seat 2020 down)relative to the position shown. In this arrangement, the movement of theball 2008 within the cavity 2018 is restricted at lower end by the ballseat 2020 and the opening 2023 is sealed when fluid pressure at adownstream plenum is not enough to lift the ball 2008. When fluidpressure becomes sufficient, the ball 2008 is lifted from the seat 2020and the opening 2023 allows fluid flow, thereby reducing the pressure inthe plenum.

It should be understood that the foregoing embodiments of the ballbearing contact assembly 1900 or merely illustrative. A variety ofadditional and/or alternative embodiments are contemplated. For example,in one embodiment the ball bearing contact assembly 1900 may include twoor more balls disposed in the housing 2006. In another embodiment, abiasing member may be disposed to engage the ball 2008 and urged theball 2008 in a particular direction. For example, a spring may bedisposed at an upper end of the set screw 2022 to urge the ball 2008against the ball seat 2020 even in the absence of sufficient backsidefluid pressure. In another embodiment, the set screw 2022 is itselfspring-loaded to tolerate some adjustment in the position of the setscrew relative to the cover plate 2010. In yet another embodiment, abiasing member may be disposed between the ball 2008 and the ball seat2020 to urge the ball downward against the set screw 2022. In the latterembodiment, the ball is urged upward toward the ball seat 2020 in thepresence of a sufficient fluid pressure which overcomes the biasingforce of the biasing member. Further, the rotating member in the housing2006 may be any rotatable member and need not be a ball. For example,the assemblies 1900 may be roller bearing assemblies in which case thehousing 2006 houses one or more rollers, i.e., generally cylindricalmembers. The roller(s) may operate in a manner similar to the ball 2008except that, in one embodiment, the roller only rotates about itslongitudinal axis. In this case, the roller is preferably orientedorthogonal to the direction of rotation of the substrate relative to thepolishing article. In another embodiment, an additional degree ofrotation is provided by allowing the housing 2006 to rotate relative tothe pad upper polishing pad 1902, the lower support pad 1904 and asubstrate being polished.

Referring now to FIG. 21, another embodiment of the ball bearing contactassembly 1900 shown in a side cross sectional view. Where possible, likenumerals have been used for simplicity. Accordingly, components whichhave been described above will not be described again, except to noteparticular differences, where appropriate or if necessary.

In the embodiment of FIG. 21, a contact plate 2150 and a support plate2152 are located at one end of the housing 2006. In one embodiment, thecontact plate 2150 and the support plate 2152 are pressure fitted withinthe housing 2006. The contact plate 2150 and support plate 2152 eachhave openings formed therein which are registered with one another toform a common fluid port 2154.

A contact assembly 2156 is disposed between the contact plate 2150 andsupport plate 2152. One embodiment of the contact assembly 2156 and thesupport plate 2152 is shown in an exploded view in FIG. 22. In general,the contact assembly 2156 comprises a body 2158, one or more flexiblebiasing members 2160A (three shown by way of illustration) and a contactelement 2162A attached to an upper end of each of the flexible biasingmembers 2160A. The body 2158 defines an opening 2159 which makes up aportion of the fluid port 2154. Illustratively, three contact elements2162A and their respective biasing members 2160A are shown spacedequidistant from one another, i.e., 120 degrees apart. In thisconfiguration the contact elements 2162A and their respective biasingmembers 2160A confine the ball 2008 to a central region of the cavity2018. More generally, any number and positional configuration of biasingmembers 2160A/contact elements 2162A may be used to advantage.

Illustratively, the contact elements 2162A comprise a hemisphericalmember attached to a flexible arm 2164 of the respective biasing member2160. FIG. 23 shows another embodiment in which the body 2158, thebiasing members 2160B and the contact elements 2162B form a solidintegrated component. Further, the contact elements 2162B are generallyelongated curved members, such as a cylinder section. In any case, thecontact elements 2162A-B are preferably smooth electrically conductivemembers which may be brought into low friction contact with the ball2008.

With reference again to FIG. 22, note that the support plate 2152 has arecess 2270 to accommodate each of the biasing members 2160. Therecesses 2270 are in part defined by an inner wall 2272 against whichthe biasing members 2160 may abut. In this way, the inner wall 2272serves as a stop to delimit the range of motion of the biasing member2160 in at least one direction (i.e., in an inward direction towards acenter of the contact assembly 2156).

Preferably, the contact plate 2150 and the contact assembly 2156 areeach made of conducting materials. For example, the contact plate 2150may be made of copper while the body of the contact assembly 2156 may bemade of the same or some other conductive material. The contact elementsare preferably made of (i.e., either solid or plated with) a noble metalsuch as gold, platinum or titanium. In this configuration, the powersupply 150 may be coupled to the contact plate 2150 and allow currentflow to the contact elements, when a closed circuit is established.

In FIG. 21, the ball 2008 is shown separated from (i.e., not in contactwith) the contact element 2162 and a portion of the ball 2008 isextended over the polishing surface (represented by plane 2030). In oneembodiment, the ball 2008 is maintained in the separated position byoperation of gravity, where configured for face up polishing. Where theball bearing contact assembly 1900 is configured for face down polishingthe separated position may be maintained by fluid pressure. In otherwords, fluid is flowed into the cavity 2018 through the fluid port 2154,thereby forcing the ball 2008 against the tapered surface 2020. In thisposition, the contact between the ball 2008 and tapered surface 2020creates a seal which can be maintained by continuing hydrostaticpressure in the cavity 2018. The ball 2008 may also be urged below thepolishing surface, such as by the force of a substrate being polished,so that contact is made between the ball 2008 and the contact element2162. This contact position is shown by the dashed lines 2008′.

Whether the ball bearing contact assembly 1900 is configured for face upor face down polishing, the polishing operation is substantially thesame. For purposes of describing one possible operation, it will beassumed that the ball 2008 is initially in the separated position andthat sufficient hydrostatic pressure is provided to maintain thisposition, even where gravity provides a counteracting force (in the caseof face down polishing). In this position, substantial electricalcommunication between the power supply 150 and the ball 2008 is notpresent as a result of the separation between the contact element 2162and the ball 2008. Of course, some degree of current flow via the ball2008 may be made possible to the extent that the surrounding electrolyteis capable of supporting a current. A substrate to be polished is thenbrought into contact with the upper surface of the polishing pad 1902.The position of lower surface of the substrate is illustrated by theplane 2030, which is substantially coplanar with the upper surface ofthe polishing pad 1902. In this position, contact is made between theball 2008 and the contact element 2162. Accordingly, a closed-circuit isnow established between the anode (i.e. power supply 150) and thecathode (i.e. the substrate). Further, fluid flow is permitted aroundthe ball 2008 and through the upper opening 2023 of the housing 2006.Either or both the substrate and the pad 1902 may be actuated (e.g.,rotated) to provide relative movement between the substrate and the pad.During such relative movement electrical contact between the ball 2008and the contact element 2162 is maintained. Persons skilled in the artwill recognize that good electrical contact is maintained between theball 2008 and the contact element 2162, even in the event of slightaxial movement of the ball 2008, by appropriate positioning of thecontact element 2162. Further, it is generally preferable to maintaingood electrical contact between the ball 2008 and the contact element2404 with minimal physical pressure therebetween. The particular degreeof pressure resulting from contact between the ball 2008 and the contactelement 2162 may be determined by the positioning of the respectiveelements and the flexibility (e.g., spring constant) of the biasingmembers 2160.

At the end of the polishing cycle and/or rinse cycle, the substrate maybe removed from the polishing pad 1902. If fluid flow through the fluidport 2028 is not terminated, and if sufficient backside pressure isavailable, the ball 2008 is urged up against the ball seat 2020. In thisposition, the ball 2008 substantially restricts or prevents fluid flowthrough the housing opening 2023. As such, the ball 2008 operates as acheck valve to conserve electrolyte between polishing cycles.

FIG. 24 shows yet another embodiment of the ball bearing contactassembly 1900. Where possible, like numerals have been used forsimplicity. Accordingly, components which have been described above willnot be described again, except to note particular differences, whereappropriate or if necessary.

In general, the ball bearing contact assembly 1900 shown in FIG. 24comprises the ball 2008′, a biasing member 2402 and a contact element2404. In general, the ball 2008, the biasing member 2402 and the contactelement 2404 are all current-conducting members. As such, these membersmay be made of conducting materials such as metal. In a particularembodiment, the ball 2008 is a plastic or steel core plated with gold.In another embodiment, the ball 2008 is solid gold. Further, either orboth the biasing element 2402 and the contact element 2404 may includegold. In any case, the biasing element 2402 is connected to the powersupply 150 to provide a current to the contact element 2404 and the ball2008.

The movement of the ball 2008 within the cavity 2018 is restricted atone end by the ball seat 2020 and at another end by the biasing member2402, which carries the contact element 2404. The biasing member 2402may be any flexible member providing some degree of linear compressionin response to pressure from the ball 2008. For example, in theembodiment illustrated in FIG. 24, the biasing member 2402 is a spring.In this case, the lower end of the spring 2402 may be supported on aledge 2146 of the housing 2006. To avoid sliding of the spring 2402within the cavity 2018, the spring 2402 is preferably affixed to theledge 2146.

In FIG. 24, the ball 2008 is shown separated from (i.e., not in contactwith) the contact element 2026 by a distance 2404 and a portion of theball 2008 is extended over the polishing surface (represented by plane2030). In one embodiment, the ball 2008 is maintained in the separatedposition by operation of gravity, where configured for face uppolishing. Where the ball bearing contact assembly 1900 is configuredfor face down polishing the separated position may be maintained byfluid pressure. In other words, fluid is flowed into the cavity 2018from a lower end of the housing 2006, thereby forcing the ball 2008against the tapered surface 2020. In this position, the contact betweenthe ball 2008 and tapered surface 2020 creates a seal which can bemaintained by continuing hydrostatic pressure in the cavity 2018. Theball 2008 may also be urged below the polishing surface, such as by theforce of a substrate being polished, so that contact is made between theball 2008 and the contact element 2404. This contact position is shownby the dashed lines 2008′.

Whether the ball bearing contact assembly 1900 is configured for face upor face down polishing, the polishing operation is substantially thesame. For purposes of describing one possible operation, it will beassumed that the ball 2008 is initially in the separated position andthat sufficient hydrostatic pressure is provided to maintain thisposition, even where gravity provides a counteracting force (in the caseof face down polishing). In this position, substantial electricalcommunication between the power supply 150 and the ball 2008 is notpresent as a result of the gap 2406. Of course, some degree of currentflow via the ball 2008 may be made possible to the extent that thesurrounding electrolyte is capable of supporting a current. A substrateto be polished is then brought into contact with the upper surface ofthe polishing pad 1902. The position of lower surface of the substrateis illustrated by the plane 2030, which is substantially coplanar withthe upper surface of the polishing pad 1902. In this position, contactis made between the ball 2008 and the contact element 2404. Accordingly,a closed-circuit is now established between the anode (i.e. power supply150) and the cathode (i.e. the substrate). Further, fluid flow ispermitted around the ball 2008 and through the upper opening 2023 of thehousing 2006. Either or both the substrate and the pad 1902 may beactuated (e.g., rotated) to provide relative movement between thesubstrate and the pad. During such relative movement electrical contactbetween the ball 2008 and the contact element 2404 is maintained.Persons skilled in the art will recognize that good electrical contactis maintained between the ball 2008 and the contact element 2404, evenin the event of slight axial movement of the ball 2008, by appropriatepositioning of the contact element 2404. Further, it is generallypreferable to maintain good electrical contact between the ball 2008 andthe contact element 2404 with minimal physical pressure therebetween.The particular degree of pressure resulting from contact between theball 2008 and the contact element 2404 may be determined by thepositioning of the respective elements and the spring constant of thebiasing member 2402.

For each of the foregoing embodiments, the substrate may be removed fromthe polishing pad 1902 at the end of the polishing cycle and/or rinsecycle. If fluid flow through the cavity 2018 is not terminated, and ifsufficient backside pressure is available, the ball 2008 is urged upagainst the ball seat 2020. In this position (indicated by the dashedlines 2008″ in the embodiment of FIG. 20), the ball 2008 substantiallyrestricts or prevents fluid flow through the housing opening 2023. Assuch, the ball 2008 operates as a check valve. Such an arrangement maybe desirable, for example, to conserve electrolyte between polishingcycles. Accordingly, when the next substrate is brought into contactwith the ball 2008, the ball is depressed into the cavity 2018 and intothe position 2008′. In this position, fluid flow is permitted throughthe opening 2023.

For each of the foregoing embodiments, the ball 2008 and the contactelement(s) 2026, 2404, 2162 are only in selective electrical contact.For example, when the ball 2008 is urged against the seat 2020 (theposition indicated by the dashed lines 2008″ in the case of FIG. 20), nophysical (and hence, electrical) contact is made between the ball 2008and the contact element(s) 2026, 2404, 2162. Contact between the ball2008 and the contact elements 2026, 2404, 2162 is then made only when asubstrate (or some other object) urges the ball into the cavity 2018 andagainst the contact element. In this way, the assembly 1900 operates asa switch, whereby a current flow path between the ball 2008 and thepower supply 150 is only selectively established. This configuration mayprevent or mitigate etching of the balls 2008 which are not in contactwith a substrate being polished.

In some embodiments it may be desirable to adjust the height of thecontact elements, such as the balls 2008 described above. At least oneheight adjustment mechanism was described above with respect to FIG. 20in which a set screw 2022 is provided to adjust a lower positional limitof the ball 2008 within the cavity 2018. However, any variety of otherheight adjustment mechanisms are contemplated, including mechanismswhich adjust the height of the contact element (e.g., the ball 2008), astructure containing or supporting the contact element (e.g., thehousing 2006) or both.

Power Supply and Control

For various embodiments of the conductive polishing article 205described above, power must be coupled to the conductive elementsdisposed on the polishing article 205. One embodiment suitable forproviding power is described with reference to FIG. 25 which shows a topview of the polishing article 205. A power strip 2502 and conductingmembers 2504 (eight shown) are used to provide a current to thepolishing article 205. The power strip 2502 and the conducting members2504 may be of any sufficiently conductive material, such as copper. Thepower strip 2502 is connected at one end to the power supply 150 and addanother end to an anchor 2505. The anchor may be any insulated member.Illustratively, a portion of the power strip (indicated by arc length2506) is wrapped around a circumferential edge of the polishing article205. The conducting members 2504 are generally radially disposed from acenter 2508 of the polishing article 205 to the edge of the conductivepolishing article 205. The terminal ends of the conducting members 2504at the edge of the conductive polish article 205 are sufficientlyexposed to make electrical contact with the conducting strip 2502. Tothis end, the conducting members 2504 may extend slightly beyond theedge of the polishing article 205. In this manner, the power strip 2502is capable of providing a current to any conductive element(s) 2504 ofthe polishing article 205 with which it comes into contact with.

In one embodiment, the conducting members 2504 comprise the embedded padinserts/assemblies shown in FIGS. 3-12 and described above. In anotherembodiment, the conducting members 2504 are electrically connected toother contact elements disposed on the polishing article 205 including,for example, those elements described with reference to FIGS. 3-12. Inany case, it should be noted that, at least in one embodiment, theconducting members are electrically isolated from one another (note thatin FIG. 25 the conducting members to not touch at the center of thepolishing article 205). This allows, at any given time, some of theconducting members to be positively biased by contact with the powerstrip, while other conducting members are not biased.

In operation, a substrate 2510 is brought into contacting with the upperpolishing surface of the polishing article 205 while the polishingmedium is rotated about its center axis. In some embodiments, thesubstrate may be moved relative to the polishing article 205 by actionof the polishing head 130. However, in order to ensure anodicdissolution, the substrate's position should be constrained to a regionin which contact with one of the energized conducting members (that is,one of the conducting members currently in contact with the power strip)is made. Those conducting members not in direct contact with the powerstrip, or indirect contact with the power strip via the substrate, willnot experience a positive bias, or at least a relatively smaller bias.As a result, electrochemical attack and damage of the conducting membersand any conductive elements electrically connected thereto is reduced.In one embodiment, any one of the conductive members and power strip areelectrically connected for between about 20% and 60% of the rotationperiod of the polishing article 205.

Typically, the highest potential on the conducting members is closest tothe power strip and the lowest potential is at the end of the conductingmembers closest to the center of the polishing article 205. Accordingly,in order to ensure an equipotential surface along the length of theconducting members, and therefore over the surface of the contactingsubstrate, the conducting members may be of increasing conductivity fromthe edge of the polishing article 205 to the center 2508. In some cases,substrate rotation relative to the polishing pad will equalize oraverage out the potential imparted to the substrate surface to providefor more uniform material deposition rate or removal rate.

Over time, the power strip contacting the edge of the polishing article205 may become worn. Accordingly, it may be necessary to replace orrecondition the power strip. To this end, the anchor 2505 may beequipped with a power strip dispenser. A mechanism may be provided onthe other end of the power strip to take up slack when a length of powerstrip is dispensed from the power strip dispenser.

FIG. 26 shows a top view of another embodiment of the polishing article205 in which power is coupled from the power supply 150 to a substrate(not shown) being polished. As in the embodiment described above withreference to FIG. 25, the polishing article 205 includes a plurality ofelectrically isolated conducting members 2504. A plurality of conductivering portions 2602A-D (four shown, by way of illustration) are disposedat the perimeter of the polishing area of the polishing article 205. Thering portions 2602 are in electrical communication with the one or moreconducting members 2504. However, the ring portions 2602 are isolatedfrom one another by gaps 2604A-D. Although not shown, in one embodimentinsulating material is disposed within the gaps to prevent arcingbetween the ring portions. Periodic electrical contact is made betweenthe ring portions 2602 and the power supply 150 via a contact finger2606 connected to a flexible arm 2608. The flexible arm 2608 provides amechanical bias against the ring portions 2602 to ensure adequatecontact. In one embodiment, the conductive ring portions are embeddedwithin the perimeter edge of the polishing article 205, but exposed toallow contact with the contact finger 2606.

In operation, a substrate is placed into contact with the upperpolishing surface of the rotating polishing article 205. At any giventime, a selective positive bias is provided to one or more of theconductive ring portions 2602, and therefore, the associated (i.e.electrically connected) conducting members 2504. To ensure anodicdissolution, the substrate is positioned to be in electrical contactwith the appropriate conducting members 2504. During rotation of thepolishing article 205, one or more of the conducting members 2504 willbe positively biased, while the other conducting members will beunbiased. In this manner, electrochemical damage to any of theconducting portions of the polishing article 205 is reduced.

Contacts: Materials

The materials used for contacts (e.g., the wire contacts of FIGS. 3-12)and the roller/ball contacts of FIGS. 13-24) taught, shown or suggestedherein may be selected according to suitability to a particularapplication. For example, good conductivity and resistance todissolution may be considered desirable characteristics. Further, lowsurface roughness may be desirable to avoid scratching the surface ofthe substrate being polished. Accordingly, any variety of materials arecontemplated for use according to aspects of the present invention. Byway of example, some materials have been recited above with respect toparticular embodiments. More generally, preferred materials includemetals, and more particularly, noble metals such as gold, platinum andtitanium. Other materials include iridium (Ir) and rhodium (Rh). In someembodiments, inert materials such as graphite may be used. With regardto conductive materials, the contact elements may be solid or plated.For example, in one embodiment the wire contacts (FIGS. 3-12) comprise aflexible non-conductive material (e.g., nylon fiber) coated with a noblemetal. In a particular embodiment, the non-conductive material isTorlon®, a glass filled polyamide/polyimide available fromMcMaster-Carr, Inc.

Persons skilled in the art will recognize that the foregoing embodimentsare merely illustrative. The invention contemplates and admits of manyother embodiments. For example, a number of the foregoing embodimentsdescribed a face down electropolishing technique. That is, the substrateto be processed is in a face down orientation relative to the polishingpad. However, in other embodiments, face up electropolishing techniquesare employed. These and other embodiments are considered within thescope of the invention. Further, persons skilled in the art willrecognize that aspects of various embodiments have been separatelydescribed/shown. However, each of the embodiments may be combined or beemployed in the alternative with respect to other embodiments. Forexample, wire contacts in the form of arches (See FIGS. 3 and 4) andtwisted (or partially twisted) loops/arches (See FIG. 5 and FIGS. 11 and12) have been disclosed. Accordingly, it is contemplated that otherembodiments showing wire arches may instead be configured as wiretwisted loops.

For purposes of illustration some embodiments disclosed herein may havebeen described using terms such as over, under, below, adjacent, and thelike. Such terms are used to indicate relative location. As such, therecited location of an entity is not limiting of any embodiment of theinvention and other relative locations are contemplated and are withinthe scope of the invention.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method for electrochemical processing a substrate comprising aconductive surface, the method comprising: providing a pad body having aconductive rotating contact element extending from a polishing surfaceof the pad body; placing the conductive surface of the substrate incontact with the polishing surface of a pad and the conductive rotatingcontact element; delivering a current through the conductive rotatingcontact element to the conductive surface of the substrate; causingrelative motion between the substrate and the pad, whereby theconductive rotating contact element is adapted to rotate while incontact with the substrate, wherein the conductive rotating contactelement is disposed in a fluid channel formed in the pad; and flowing anelectrolyte through the fluid flow channel to actuate the conductiverotating contact element.
 2. The method of claim 1, wherein placing theconductive surface of the substrate in contact with the conductiverotating contact element further comprises: compressing a flexiblebiasing member supporting the conductive rotating contact element.
 3. Amethod for electrochemical processing a substrate comprising aconductive surface, the method comprising: providing a pad body having aconductive rotating contact element extending from a polishing surfaceof the pad body; placing the conductive surface of the substrate incontact with the polishing surface of pad and the conductive rotatingcontact element; delivering a current through the conductive rotatingcontact element to the conductive surface of the substrate; and causingrelative motion between the substrate and the pad, whereby theconductive rotating contact element is adapted to rotate while incontact with the substrate, wherein placing the conductive surface ofthe substrate in contact with the conductive rotating contact elementcomprises hydro-dynamically actuating the conductive rotating contactelement.
 4. The method of claim 1, further comprising: submersing thepolishing surface below an upper fluid level of electrolyte contained ina tank.
 5. The method of claim 1, further comprising: flowingelectrolyte through a plurality of fluid channels formed in the pad. 6.The method of claim 1, wherein causing relative motion between thesubstrate and the pad is done in the presence of electrolyte.
 7. Themethod of claim 1, wherein at least a portion of the conductive rotatingcontact element comprises gold.